Does the radon and iradon built in functions use the center as the reference for the projections?

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oumi k 2023-4-2

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评论： oumi k 2023-4-3

For example in this image how can iradon function differentiate between P0(0)=3 and P0(1)=7 since both projections are taken horizontally?

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Image Analyst 2023-4-3

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No it doesn't use the center. It's as if you had a whole army of those rays, all parallel to each other. The arrowheads land on a 1-D array. So essentially each pixel in the array is the sum of all pixel values along the ray perpendicular to that point in the array that passes through your "body".

The "3" and "7" rays are different because they each passed though a different "path" through the body and ended up on a different pixel in the 1-D array.

Real CT instruments no longer pass a 1-D set of rays through the body. They pass a 2-D set of rays through, like a pyramidal cone, so the radon transform (the projection) is also a 2-D image.